An observation apparatus includes a light radiating unit that radiates a plurality of element lights, each of which has a limited wavelength band, to an observation target; a light detecting unit that detects the plurality of element lights reflected by the observation target in a plurality of patterns by changing a weight for each of the element lights; and a processing unit that performs a procedure of separating a component of each of the element lights from a plurality of detection results of the light detecting unit based on the weight for each of the element lights of the light detecting unit.